T mitogens trigger LPS responsiveness in mouse thymus cells.

Mouse thymus cells are essentially unresponsive to lipopolysaccharide (LPS) stimulation. However, when cultured with minimally mitogenic levels of concanavalin A or submitogenic ratios of mitomycin-treated allogeneic spleen cells, in combination with LPS, they demonstrate levels of DNA synthesis de novo or greater than those induced by the T cell mitogen alone. Dose-response kinetics were characteristic of LPS. The subpopulation containing the LPS responsive cells was of low net buoyant density. Neither phytohemagglutinin nor pokeweed mitogen acted synergistically with LPS in this model to trigger thymus cells. The data suggest that LPS triggering may involve interaction with a T cell subpopulation.     

Effects of growth temperature on photosynthetic carbon metabolism in green plants II. Photsoynthetic 14CO2-incorporation in plants acclimatized to varied temperatures

During photosynthetic ¹⁴CO₂-fixation, leaves of plants suchas wheat, the broad bean and spinach, which had been acclimatizedto high temperature (20–25?C), incorporated much moreradioactivity into sucrose, and less into glycine and serinein comparison with similar plants grown in the cold (mean temperature,5–7?C). Radioactivities incorporated into glycine and serine greatlydescreased on the addition of -hydroxyethylsulfonate or on theremoval of oxygen from the atmosphere, indicating that thesecompounds are synthesized through the glycolate pathway. In leaves of wheat grown under low temperatures, relativelyhigh radioactivity was detected in ribulose 1,5-diphosphateamong the photosynthetic ¹⁴CO₂-fixation products, whereas practicallyno radioactivity was detected in this compound in leaves ofwheat which had been acclimatized to high temperatures. We assumedthat the carboxylation reaction of ribulose 1,5-diphosphateis suppressed in plants acclimatized to low temperatures. It was further inferred that the C-2 and C-2 moiety of ribulose1,5-diphosphate accumulating as a result of suppression of carboxylationis converted to glycine and serine through the glycolate pathway. The possibility was also discussed that during photosyntheticCO₂-fixation in wheat leaves at least a part of the C₆-compoundformed by the carboxylation of ribulose 1,5-diphosphate is directlyconverted to sugar phosphate. ¹Part of this investigation was reported at the 2nd InternationalCongress on Photosynthesis Research at Stresa, Italy, June 1971.This paper is based on a dissertation submitted by S.S. to theFaculty of Science, the University of Tokyo, in partial fulfilmentof the requirements for a Ph.D. degree. ²Present address: Department of Botany, Faculty of Science,University of Tokyo, Tokyo, Japan. (Received July 20, 1973; )     

Effects of growth temperature on photosynthetic carbon metabolism in green plants III. Differences in structure, photosynthetic activities and activities of ribulose diphosphate carboxylase and glycolate oxidase in leaves of wheat grown under varied temperatures

The rate of ferricyanide photoreduction in broken chloroplastsisolated from leaves of wheat acclimatized to a low temperature(mean temperature, 5–7?C) was similar to that in chloroplastsfrom wheat acclimatized to a high temperature (20–25?C). There was no practical difference in glycolate oxidase activityin leaf extracts of wheat plants grown at low and high temperatures.In contrast, the ribulose diphosphate carboxylase activity ofchloroplasts from low temperature sample was less than halfthat for the high temperature sample. Chloroplasts having a high rate of photosynthetic CO₂-fixationwere obtained from wheat acclimatized to a low temperature,whereas the CO₂-fixation activity in chloroplasts isolated fromhigh temperature-acclimatized wheat was very low. Electron microscopy revealed that chloroplasts in high temperature-acclimatizedwheat were ellipsoidal, electron dense and contained starchgranules. Those in low temperature-acclimatized leaves wereround and did not contain starch granule. ²Present address: Department of Botany, Faculty of Science,University of Tokyo, Tokyo, Japan (Received August 7, 1973; )     

Protein components of two different regions of an intestinal epithelial cell membrane: Regional singularities

The two different regions of the plasma membrane, i.e. apical and basolateral membranes, of intestinal epithelial cells were analyzed as to their proten components. They showed very contrasting profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The apical membranes possessed several major components with apparent molecular weights larger than 108 000, most of which were also periodic acid-Schiff reagent positive. In contrast, there were no protein components with corresponding molecular weights in the basolateral membrane. The electrophoretic profile of the latter was strinkingly simple. The dominant band was assigned a molecular weight of 101 000 and was periodic acid-Schiff reagent negative. No major components were shared by the two membranes.     

Cytodifferentiation of the adenohypophysis of the domestic fowl

Summary In the chick embryo the first membrane-bound secretory granules occur in the cytoplasm of occasional cells in the cephalic lobe of pars distalis at the 7th day of incubation. On the 8th day most of the cells in both the cephalic and caudal lobes contain secretory granules that are variable in size, form and density.On the 9th day at least two types of glandular cells are distinguishable in the cephalic and in the caudal lobes; however, these cells are not comparable with those of the adult gland. Differentiation of acidophils and basophils occurs, apparently simultaneously, in 11-day embryos.The cells of the cephalic and caudal lobes are morphologically distinct from their first appearance. Thus it is concluded that these two lobes develop independently and differently from an early stage of ontogenesis.The secretory granules are formed in the Golgi area of the hypophysial cells after the 8th day of incubation. However, secretory material may be synthesized also by a process not involving the Golgi apparatus.Nerve fibers containing granules first appear in the superficial layer of the median eminence on the 8th embryonic day and by the 12th day three types of granules and two types of clear vesicles are identifiable.The investigation reported herein was supported by grant from Japan-U.S. Cooperative Science Program of Japan Association for Science Promotion to Professor Mikami and by U.S.-Japan Cooperative Science Program Grant No. GF-33334 to Professor Farner.     

Effect of d-Limonene and related compounds on bile flow and biliary lipid composition in rats and dogs

d-Limonene enhanced bile flow in rats and dogs with a dose response correlation. The choleretic activity was much higher in the metabolites of d-limonene such as p-mentha-1,8-dien-10-ol, p-menth-1-ene-8,9-diol and p-mentha-1,8-dien-6-ol than d-limonene, and this suggested that the choleretic activity of d-limonene was attributable at least in part to its metabolites.The choleretic activities of esters of p-menth-1-ene-8,9-diol with acetic acid, propionic acid, stearic acid, palmitic acid, linoleic acid, benzoic acid, salicylic acid, α-naphthylacetic acid and nicotinic acid were also investigated in rats. Among these compounds, acetate, propionate and nicotinate possessed considerable, but lesser activities than the original diol. In dogs, however, the choleretic activity of p-menth-l-ene-8,9-diol acetate and propionate was much higher than that of original diol, suggesting that the choleretic activity of these esters is attributable to the esters themselves.d-Limonene decreased the ratio of biliary bile salts and phospholipids to cholesterol, whereas p-menth-l-ene-8,9-diol increased it.     

Changes in intracellular UDP-sugar levels during the cell cycle in a synchronous culture of Catharanthus roseus

UDP-sugar contents were measured using high performance liquid chromatography and gas chromatography during the cell cycle in a synchronous culture of Catharanthus roseus (L.) G. Don. UDP-glucose, UDP-galactose, UDP-glucuronic acid, UDP-xylose and UDP-arabinose could be determined, and 75–90% of the UDP-sugars were UDP-glucose. The contents of UDP-glucose and UDP-galactose increased in the late G2-M and the late S-M phases, respectively, whereas UDP-glucoronic acid and UDP-arabinose increased in amount in the G1 phase. These changes in the levels of UDP-sugars during the cell cycle generally correlated well with the changes in cell wall constituents and in the activities of the enzyme involved in synthesis and interconversion of UDP-sugars reported by S. Amino et al. (Physiol. Plant. 1985. 64: 111–117).     

Acute differential sensitivity and role of the central nervous system in the feeding behavior of Drosophila melanogaster

Feeding behavior of the fruitfly, Drosophila melanogaster, isexamined quantitatively by determining the amount of fool intakecolorimetrically. The obtained differential sensitivity (Weberfraction l/l = 0.025) by the two-choice test is surprisinglyacute, compared with the previously reported values for insects.Besides, files also choose only the most stimulative prey inthree-choice tests and even a single fly, free from ‘gangingup’ exhibits a clear intake choice. Adaptation in thetest organ was experimentally proved not to play a leading rolein ingestion choice. The present experimental results supportan important role of the central nervous system in choice behavior.Although deprivation significantly enhances the amount of ingestion,it does not affect the choice itself under the present conditions,suggesting that the choice centre exists separately from theingestion center. Discrimination sensitivity depends considerablyon the food distribution and taste intensities paired.